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Brompton 130mm with normal external gearing

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Brompton 130mm with normal external gearing

Old 09-10-22, 10:25 AM
  #51  
hihi2u2
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Originally Posted by 2_i View Post
Congratulations on getting there and this on your own. I wonder about the situation with the chain on the lowest cog. How far is the tensioner arm then from the ground? Can you fold then fine without the chain getting loose or do you need to watch on which cog you need to fold? With the bottom bracket, was that that the chainline was off? Did you try asymmetric placement of the bracket, different amounts of sticking out to the left than right? What is the cassette you ended up using? Thanks.
If you find the right chain length then the rear derailleur clears the ground. The Ltwoo derailleur is supposed to support up to 28T but I've got a 32T on it, so it is closer to the ground than it is designed but it still clears it. I haven't had any chain strike yet.

All cogs is ok to fold without an issue but third and fourth is better for me as my wheel is deep section so the derailleur scratches my wheel. Third and fourth cog will result in a more compact derailleur.

In terms of bottom bracket, Ive added around 5mm of spacer to clear the rear triangle. I haven't had any skipping of gears and it shifts perfectly so it seems all fine. But you would need a hollowtech, square taper definitely won't work.

The rear derailleur does come in 7 speed as well. So the less modding option is to get a 7 speed wheel and just put the Ltwoo derailleur on it.

Another thing to mention, the smallest cog does catch the frame so I had to sand off 1-2mm off the bike. Using 11 speed chain will run better in my experience for the same reason.

I've bought the Ltwoo Folo B derailleur set from AliExpress.
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Old 09-10-22, 11:10 AM
  #52  
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Originally Posted by hihi2u2 View Post
The Ltwoo derailleur is supposed to support up to 28T but I've got a 32T on it, so it is closer to the ground than it is designed but it still clears it. I haven't had any chain strike yet.

Another thing to mention, the smallest cog does catch the frame so I had to sand off 1-2mm off the bike. Using 11 speed chain will run better in my experience for the same reason.

I've bought the Ltwoo Folo B derailleur set from AliExpress.
Thanks for the details. I have the rear derailleur coming close to the ground on my Bike Friday NWT, but no mishap there yet either. Still, it makes me uncomfortable and I ponder now switching to Ltwoo Folo there (20" wheels), maybe buying me comfortable clearance from the ground. However, NWT also has 3 rings in the front and maybe Ltwoo lacks enough capacity. I may just get it and have it as an option with different bikes .

Rather than filing the frame, you might have put a washer onto the axle from inside, still requiring 1-2mm more spread.
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Old 09-17-22, 04:23 AM
  #53  
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Originally Posted by 2_i View Post
Thanks for the details. I have the rear derailleur coming close to the ground on my Bike Friday NWT, but no mishap there yet either. Still, it makes me uncomfortable and I ponder now switching to Ltwoo Folo there (20" wheels), maybe buying me comfortable clearance from the ground. However, NWT also has 3 rings in the front and maybe Ltwoo lacks enough capacity. I may just get it and have it as an option with different bikes .

Rather than filing the frame, you might have put a washer onto the axle from inside, still requiring 1-2mm more spread.
I've done the spacer in the axle already, it just clears but catches ever so slightly. It's just sanding probably less than 1mm, is better that than to let my chain do the sanding.

The Ltwoo is only 40 so can't really go wrong if you want to try it out.
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Old 09-17-22, 07:05 AM
  #54  
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Originally Posted by Jipe View Post
No, I do not have it.

The problem was that bending the base without flattening the tube of the titanium triangle was more difficult than with the steel base due to the higher elasticity of titanium.
I think you have this backwards, the problem is /was the lower modulus of elasticity of titanium than steel. Titanium has the same strength, but bends more for the same force. It is more flexible.
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Old 09-17-22, 03:03 PM
  #55  
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Originally Posted by hihi2u2 View Post
Finally finished building my bike.
In the end I've ended up using Ltwoo Folo B rear derailleur with jockey wheel and tensioner designed for Brompton. The fold works really well and the shifting is very smooth.
From the appearance in the photo, your derailleur seems to have a plastic tensioner arm. Is that right? The price you quote seems to also point in that direction. However, Ltwoo seems also to have a version of this (or practically the same) derailleur with an alloy tensioner arm. Have you had any thoughts leaning towards one or other version, before or after the purchase? In my mind the tension is between the nominal long-term durability, as plastic ages, and the real life practical day-to-day arm survival close to the ground.
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Old 09-18-22, 03:12 AM
  #56  
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Originally Posted by 2_i View Post
From the appearance in the photo, your derailleur seems to have a plastic tensioner arm. Is that right? The price you quote seems to also point in that direction. However, Ltwoo seems also to have a version of this (or practically the same) derailleur with an alloy tensioner arm. Have you had any thoughts leaning towards one or other version, before or after the purchase? In my mind the tension is between the nominal long-term durability, as plastic ages, and the real life practical day-to-day arm survival close to the ground.
I haven't seen a metal one before but it is plastic, similar to the original Brompton which is also plastic. The tensioner arm is cleared of the ground so I don't see any issue.

It is quite a heavy derailleur to begin with, with the additional tensioner and beefier design compared to normal derailleur. So bear that in mind as well.
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Old 09-18-22, 03:28 AM
  #57  
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Industrial plastic is not a bad choice for the tensionner arm, it has some elasticity that aluminum doesn't provide, in case of a some shock against the ground, the plastic may bend and come back to its original shape where aluminum will bend and have permanent deformation.
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Old 09-18-22, 04:24 AM
  #58  
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It's true and I think Brompton's choice of a plastic tensioner is good. However, I treat it as a disposable, something I will swap in a few years for a new one. However, in the case of Brompton I am sure the replacement will be there in a few years and, if necessary, in 20 years. Even if Brompton company were not to exist, someone else would provide that tensioner. However, will Ltwoo be still around in a few years from now? If they are still around will they still provide the particular tensioner? I do not even try to think about 20 years. The best, of course, would be if they provided just the plastic arm as a replacement. This is the dilemma when you try to push a particular solution on a particular bike - a solution or actually a start for the string of solution swaps?
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Old 11-20-22, 02:20 PM
  #59  
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Originally Posted by hihi2u2 View Post
Finally finished building my bike.
In the end I've ended up using Ltwoo Folo B rear derailleur with jockey wheel and tensioner designed for Brompton. The fold works really well and the shifting is very smooth.
Originally Posted by 2_i View Post
Thanks for the details. I have the rear derailleur coming close to the ground on my Bike Friday NWT, but no mishap there yet either. Still, it makes me uncomfortable and I ponder now switching to Ltwoo Folo there (20" wheels), maybe buying me comfortable clearance from the ground. However, NWT also has 3 rings in the front and maybe Ltwoo lacks enough capacity. I may just get it and have it as an option with different bikes .
Well, I got the Ltwoo Folo B rear derailleur with the intention to try it out on my Bike Friday NWT. The derailleur is advertised as one for folding bikes, with Brompton and 3Sixty mentioned explicitly. Unfortunately, it can only function off the supplied hanger that itself mounts on the Brompton's rear wheel axle. If this derailleur is mounted on a hanger integrated with the dropout, it cannot reach the smallest cogs. The thickness of the supplied hanger, that lacks any staggering, is needed to push the derailleur out so that it can cover the full cog range. There may be some solution for the case of an integrated hanger, such as getting a longer hanger bolt and devising some spacer with a stop, but I was getting this derailleur with the hope of making the rear streamlined, not looking for more problems to solve.


What you get


On Bike Friday

Last edited by 2_i; 11-20-22 at 05:37 PM.
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Old 11-22-22, 11:54 AM
  #60  
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Hmm. I think these are 120mm OLD. The last one is a 16-speed.



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Old 11-22-22, 07:30 PM
  #61  
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I wonder if anyone tried out any of these aftermarket P-line derailleurs for C-line in practice. The prices can stop your breath and the feeble alu tensioner arms just a tire width away from the ground is disconcerting. I will be sitting out for now. Unfortunately, as of now, the original Brompton C-line derailleurs are nowhere to be seen as replacement parts.
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Old 11-23-22, 03:30 AM
  #62  
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I have big doubts about the reliability of this concept with a tensionner wheel that must move on a long axle which is exposed to dirt.

The same exist with only two cogs on the 2s and 6s Brompton and is known to be dirt sensitive. With much more cogs, the axle on which the tensionner wheel must move is much longer and much more exposed to dirt.
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Old 11-23-22, 09:19 AM
  #63  
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With the snow abundant in our area, I have been inspecting how the Brompton's tensioner wheels get impacted by the snow. It appears that the original Brompton's wheel design (as compared to aftermarket) is the most prone to getting packed with snow and pushing the chain out from the wheel as a consequence. This presumably deserves its own thread at some point.
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Old 11-29-22, 08:41 AM
  #64  
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Originally Posted by 2_i View Post
Well, I got the L-TWOO Fold B rear derailleur with the intention to try it out on my Bike Friday NWT.
Seems to work okay used as intended.


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Old 11-29-22, 09:20 AM
  #65  
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I am always cautious with those video's showing the system working without load and when its perfectly clean !

The cogs of this cassette seem relative small, what is needed to have a wider range is a biggest cog of at least 32t with a 11-32 range (unless it would be possible to mount a 10t or 9t smallest cog ?).
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